My Langrisser album confirms it.
Although, his name is spelled "Goo Hallad" in the booklet. But yes, he produced and even wrote the script for the drama tracks.
EDIT: To clarify, he only had to do with the drama tracks. As for any actual "arrangement", I can't remember what the music in the drama tracks sounds like. But I think they are the same versions as on the album.
If you'd like, I can pop the CD in some time and check. I never ripped the drama tracks to my computer because, well... they're drama tracks, and listening to them is less fun than eating nails.